The sacroiliac joint is the joint between the sacrum and the ilium of the pelvis, which are joined by ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The sacroiliac joint is a synovial joint with articular cartilage and irregular elevations and depressions that produce interlocking of the two bones.
Pain associated with the sacroiliac joint can be caused by traumatic fracture dislocation of the pelvis, degenerative arthritis, sacroiliitis, an inflammation or degenerative condition of the sacroiliac joint, osteitis condensans ilii, or other degenerative conditions of the sacroiliac joint. Currently, sacroiliac joint fusion is most commonly advocated as a surgical treatment for these conditions. Fusion of the sacroiliac joint can be accomplished by several different conventional methods. However, while each of these methods have been utilized for fixation and fusion of the sacroiliac joint over the past several decades, the methods to remove the painful degenerative aspects and to provide stability of the joint while allowing a degree of motion remains unresolved.
The sacroiliac joints are multi-planar, simultaneously rotating and translating along three axis of motion and can have six degrees of freedom secondary to the three angular and three linear motions occurring at each joint. Generally, rotation can range between about 0 to about 8 degrees. Generally, translation can range between about 0 and about 8 millimeters (“mm”).
The inventive sacroiliac joint implant system described herein provides apparatuses and methods of placement of the apparatuses in relation to the sacroiliac joint which facilitate stability while allowing an amount of motion of the sacroiliac joint.